This problem has to do with the fact that primary key indexes are not surfaced by SQL Anywhere in the BDE. If you run the stored procedure sp_statistics with your table name as a parameter(ex. sp_statistics customer), it should return all indexes on the table specified. Doing this you will see that the index on the primary key doesn't surface a index name. The way to correct this is by configuring your DSN for SQL Anywhere to allow keys to be seen. This is done by checking the check box titled Microsoft Applications(Keys in SQL statistics) in the Additional Connection Options Section of the ODBC Configuration dialog for SQL Anywhere. After setting this, when you connect to your SQL anywhere database you will be able to see primary keys and UpdateMode will work as expected.